Smart City Research Classification: A Systematic Literature Review

: In the digital era, technological advances are always evolving as well as urban problems in a city. A smart city is an implementation in dealing with urban problems by providing public services. This public service is also related to one of the uses of applications that are integrated with ICT in public services. Smart cities also have various types of applications that can be used to provide services to the community. The progress of the internet of things and big data analysis has become the infrastructure in implementing smart city applications. This study aims to classify 25 cities that implement smart cities based on smart applications used using a systematic literature review method. With this research, researchers are expected to be able to identify the types of smart city applications that are classified in each city.


Introduction
The more developing times the human population is also growing too. It is this population that creates many urban problems in each city. The development of a smart city in city can be a strategy for dealing with many urban problems (Madyatmadja et al., 2018a). The urban problem creates such as energy consumption, pollution, waste treatment and traffic. Smart cities using technology that can create opportunities for urban problems. Smart city creates strategized around the environmental, social challenge and economic. Smart city has so many concepts such as ubiquitous city, intelligent city, knowledge city, digital city and information city (Gupta et al., 2019). The urban problem is getting more and more challenging. Use help from Internet of Things (IoT), Information and Communication Technologies (ICT), Data Mining, Big Data Analytics and Data Fusion become a component to support smart city strategy (Madyatmadja et al., 2018b). Several cities worldwide have implemented smart cities such as New York to enhance the quality of water, improve the quality of resident life, reduce the environmental impacts and create more street light efficiency. London using the smart city to create smart streets to collect wide data that provide world-class connectivity and security. Paris wants to improve citizen services, digital transformation, sustainability and urbanization. There is also a city like Singapore and Tokyo that implement smart cities. Singapore wants to enhance the national digital identity of its citizens by creating e-payment systems, smart nation sensor platforms, smart urban mobility and smart community initiatives. Tokyo wants to improve transportation and other sectors of its economy. several cities in China also implemented smart city to facilitate economic and social development to build a high-income smart city (Lau et al., 2019).
Other than the city in an outside country, several cities in Indonesia have also implemented the smart city concept such as Bandung, Jakarta, Surabaya, Banda Aceh and others but not going smoothly (Firmanyah et al., 2017). This happens because some people do not understand what a smart city is, do not know how to use a smart city and do not know what benefits can be obtained from a smart city (Anindra et al., 2018). Advances in smart city technology have led to many types of applications that can be used in the various city both abroad and domestically. An application that has been raised includes smart living, smart urban area management, smart environment, smart industry, smart human mobility, smart economics and smart infrastructure. Each application has its own respective field (Lau et al., 2019).

Definition of Internet of Things
The Internet of Things is a system of internetconnected and interconnected computing devices, mechanical and digital machines that provide unique identifiers and have the ability to transfer data across networks. In a smart city, the internet of things acts as an infrastructure that is very important to support the development of smart cities. IoT provides valuable and beneficial information by various user devices through wireless and wired internet network IoT provide user-customized services, the data collected by electronic home appliances, including refrigerators, are shared and stored in a smart home environment. Various services utilizing IoT technologies in a smart city can bring about a sustainable and pleasant living environment for its citizens (Park et al., 2018).

Definition of Big Data Analysis
Big data as the name suggests is a very large piece of data that cannot be processed by traditional methods. Big data generates an incredible amount of diverse and high-speed data. The amount of data can be obtained from many sources. Big data has three component variations, namely volume, velocity and variety. It specifies that when an enormous amount of high-speed data is to be collected to process and analyze through various sources (Rathore et al., 2018)

Definition of Smart City Application
Smart city application has a lot of types and has its own respective fields such as Smart

Definition of Smart Living
Smart living increases the understanding of how people and technology can come together to bring up a decision that becomes a concept of integration:  Definition of Smart Health: Describes the digitalization of health care. By using the technology, It creates electronic health records, the development of assistive systems for the elderly and people and remote diagnostics through telemedicine  Definition of Smart Home: Incorporates sophisticated automation systems to provide occupants with detailed monitoring and control over building functions. with this smart home, people can remotely manage their homes, such as turning on lights with remote devices such as cellphones, laptops and others  Definition of Smart Community: Several cities implement smart communities such as the USA, Canada, Australia, Singapore, China and others. smart communities can be useful as state-owned systems to collect data from both public such as traffic cameras, transit data and others then as private online shopping, fitness tracker and others as data that can be used to detect user behavior that helps community welfare 

Definition of Smart Urban Management
Smart urban management can be used to handle urban areas. This smart has many types namely:  Definition of Smart Governance: Aims towards a performance improvement of administration topics, to enhance accountability and transparency. It includes egovernment, the efficiency agenda and mobile working scenarios several cities such as Singapore, Tokyo, Oslo and many others are using smart governance  Definition of Smart Urban Planning: This smart urban planning helps pay attention to the welfare of the urban population all the data that combine to understand city development sometimes this has a negative impact, namely data that is not neatly arranged but with this urban planning it can create an ideal city  Definition of Smart Building: Smart building in a city is used as a regulator in managing existing resources in buildings in a city. settings can be electricity, air conditioning, ventilation and other electronics in a building. besides managing resources in a building. a smart building can also be used as a tool for emergencies

Definition of Smart Environment
This smart environment is used to study the environment in a city. With this smart environment, we can handle urban areas such as global warming. This smart environment can also be used to calculate waste in cities Definition of Landscape Monitoring:  Landscape monitoring is used to see changes that have occurred in a city, commonly used to visualize changes that occur in a city, data sources are collected using satellites  Definition of Urban City Modeling: The use of urban city modeling is used to understand the diversity of species that exist in a city such as mountains, trees and others by using satellite data for distribution  Definition of Waste Management: This waste management is used to regulate waste pollution in a city. With this waste management, the waste can be processed and categorized from each type of waste. then waste management can monitor a polluted area from time to time

Definition of Smart Industry
With the industry standard 4.0 in the future, the industry will experience a transformation of the approach with this smart industry, so the industry can take advantage of the data collected from sensors and buildings:  Definition of Smart Manufacturing: Smart manufacturing is used to optimize the manufacturing process in a factory, such as using robots with sensors for product delivery  Definition of Smart Maintenance: Smart maintenance is useful for detecting the state of a machine whether the machine is as well as a flexible machine maintenance system by detecting errors accurately  Definition of Smart Agriculture: Smart agriculture is mainly aiming towards sustainably increasing agricultural productivity and income of farmers as well as supporting the agricultural lifecycle by implementing smart farming strategies

Definition of Smart Economics
Smart economics are used to generate commercial value in a trade, supply chain, logistic, finance center and tourism:  Definition of Smart Commerce: Smart commerce is used to help customers in a city in determining a decision when they want to buy an item. In addition to smart commerce customers, it can also help investors make investment decisions by utilizing financial data  Definition of Smart Supply Chain: The smart supply chain is used as a tracker in understanding the flow of process objects such as food with this smart supply chain, customers can check the authenticity of the food brand  Definition of Smart Tourism: This smart tourism is useful for recommending places for customers who want to travel and customers can also use this smart tourism application to track where they want to go 

Definition of Smart Human Mobility
Smart human mobility is useful for improving strategies in the transportation system with smart human mobility so we can see the movement of citizens based on the data collected:  Definition of Smart Location-Based Services: This smart location-based service is used to get an accurate position and provide navigation services for a comfortable and smooth trip with the use of technology such as smartphones  Definition of Human Mobility Understanding: Human mobility understanding is defined as solutions and services which offer the possibility for energy-efficient, low-emission, safe, comfortable and cheap mobility that can be used smartly  Definition of Smart Transportation System: smart transportation system is used to deal with congestion that occurs in a city as well as handling such as accidents

Definition of Smart infrastructure
Smart infrastructure describes the implementation of inter-connected technologies in infrastructure and the equipment they interact with:  Definition of Smart Grid: Smart grids are used to provide a stable and reliable power supply commonly used to handle and detect demand for electrical loads in certain areas, both buildings and houses in a city.  Definition of Smart Energy: Smart Energy is mainly related to the solutions and services that are integrated into the living environments and aims to foster more efficient lifestyle energy.  Definition of Smart Facility: Smart facilities are used to provide services such as parking facilities, clean water and others. These smart facilities can be useful for detecting water leaks and proposing the condition of the water data.  Definition of Smart Communication: Communication in a city is the most important thing. smart communication is useful for designing efficient and smooth communication so that people can communicate with each other without any obstacles (Lau et al., 2019)

Comparison Between Smart Cities in Developing and Developed Countries
As we know that developed and developing countries have different levels in terms of technology. Of course, developed countries have a higher level in the use of technology for smart city implementation. However, developing countries are also not inferior to the use of technology, although not as high as developed countries. Developed countries have a wealth of human resources, but as advanced as they are, countries certainly have weaknesses. One of the weaknesses of these developed countries is natural resources. Singapore is one of the developed countries that have adequate human resources but lacks natural resources, in contrast to developing countries such as Indonesia which have abundant natural resources but inadequate human resources. if Indonesia and Singapore can work together in natural resources and human resources, this has advantages in both countries, Singapore can take advantage of the natural resources owned by Indonesia and at the same time can be an example for human resources in Indonesia in processing their natural resources.

Methodology
The research method used in this study is a systematic literature review. This method is used to analyze several studies of cities from both developed and developing countries that use smart city applications and then classified into several types. Research data is taken from several sources: Link Springer, IEEE Xplore, Research Gate, Science Direct, Taylor, Sage Journal, Google Scholar, ACM, MDPI and others. the method starts from the number of studies obtained, determines the study candidate and determines the selected study from the specified candidate. Make a Venn diagram of the entire paper you are looking for. determine the author of each paper found and where the author is from and create a bar chart. Fig.1 shows Searching strategy for systematic literature review. Fig. 2 shows Diagram venn for systematic literature review.

Study Found
The first keyword is (Smart City Research Classification) obtained 64 papers then the second keyword is (smart city Internet of Things and Big data) obtained 26 papers and the third keyword is (Smart City "Country") obtained 25 papers. The total of the paper is 115 papers. Each paper is checked manually and which paper is searched for according to the topic to be worked on. Table 1 shows distribution of the selected studies.

Candidate Studies
Of all the papers that have been found, as many as 115 papers, several papers are needed to be used as candidates by adjusting the abstracts and research questions, 59 papers were found to be candidates for this study.

Decide the Selected Studies
For the selection of papers that will be used in this study, the criteria must be:  research on the identification of "Smart City" which is implemented in several cities, both developed and developing countries  The article must be related to the research question  the articles you are looking for must be published at least from 2011-2021  From the results sought, as many as 25 papers were found according to the specified criteria From the distribution table above, a Venn diagram will be made as a result of the systematic literature review. It was built using the following scheme:

Selected Studies Overview
Of the 25 papers selected, there were 90 authors with 14 institutes, 56 universities and 3 companies. here is the distribution of affiliates.
Geographically, the affiliations of each author are scattered throughout the world including Indonesia, Taiwan, Finland, France, Spanish, India, America, Korea, Canada, Singapore, Pakistan, China, Qatar, Italy, Australia, Brazil and Swedish. Figure 3 shows Distribution of affiliations. Figure 4 shows Author affiliations across the country.      (Spicer et al., 2021). 23 Paris France Smart Human Mobility Smart location-based services: Create social media location-based services provide collective projection and desires map over space (Vallicelli, 2018). 24 Jakarta Indonesia Smart Environment, Waste management: Create water level to provide information about the river condition.

Smart Human Mobility
Smart location-based service: Create GPS tracker to track transportation and CCTV to send video real time from public area Smart transportation System: Create Smart Lightning to turn on/off public street Automatically (Kusumawati et al., 2017). 25 Toronto Canada Smart Living Smart Community: Create quayside project proposed by google affiliate sidewalk labs (Spicer et al., 2021).

Conclusion
This study aims to classify the types of applications that exist in the implementation of "Smart City" in cities, both developed and developing countries. From the research that has been researched, smart city has many types of applications that can be implemented in a city for the benefit of that city. Of course, the smart city application cannot run without the help of the internet of things and big data analysis. This study classifies 25 cities that implement smart city applications. From this research, each city has many types of smart city applications according to the needs of each city. There are many types and types of smart city applications. Table 2 shows Research classifications of 25 cities in both developed and developing countries.
This study shows how smart cities in every city, both developed and developing countries, are considered implemented by looking at the definition of components and measures of city performance. We hope that this study will be useful for researchers who want to classify cities based on the smart city application implemented.